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Enhanced heat loss despite blunted renal sympathoexcitation in diabetic rats during heat stress
Author(s) -
Leite Laura Hora Rios,
Zheng Hong,
Coimbra Candido Celso,
Patel Kaushik
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.788.3
Subject(s) - medicine , endocrinology , vasoconstriction , vasodilation , mean arterial pressure , streptozotocin , heat stress , blood pressure , hyperthermia , diabetes mellitus , heart rate , zoology , biology
In the present study we investigated the effect of hyperthermia on the regulation of sympathetic activity and blood flow redistribution in diabetic rats. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), body (Tb) and tail (Ttail) temperatures were recorded in α‐chloralose‐ and urethane‐anesthetized control and streptozotocin (STZ)‐induced diabetic rats (n=6/group) during heat stress. Heat stress was induced by a heating pad with increases in temperature from 37 to 43°C during 30 min. This heat stimulus resulted in blunted RSNA, MAP and HR in diabetic rats compared with controls. The highest values were attained at the end of heat stress (ΔRSNA: 46.4 ± 10.0% vs. 155.6 ± 22.1%; MAP: 91 ± 5mmHg vs. 114 ± 5mmHg; HR: 395 ± 11bpm vs. 460 ± 11bpm; Diabetic vs Control, p< 0.05), suggesting a decreased renal vasoconstriction. Diabetic animals also showed lower Tb during the first 13 min of heat stress and decreased heat storage rate (HSR: 15.9 ± 1.6cal.min −1 Diabetic vs. 22.0 ± 0.9cal.min −1 Control; p< 0.01). These results may be due to improved heat dissipation shown by diabetic rats as indicated by a decreased ΔTb until tail vasodilation (0.3 ± 0.1°C Diabetic vs. 0.7 ± 0.1 °C Control; p< 0.02). In conclusion, although diabetic rats have a decreased RSNA response (renal vasoconstriction), the tail vasodilation was sufficient to decrease Tb and HSR to heat stress. Supported by: CNPq , NIH (HL‐62222)